Agree with your overall point Ken, but in half of those cases (F-5, A-4) I'd suggest that it was fighters being used as trainers, rather than the other way around.
That said, I think the distinctions are somewhat artificial in many cases. It is interesting to note that both the M-346 and Yak-130 were born out of a joint design, yet the former is a trainer with a secondary light attack/fighter capability, while the latter is a light attack/fighter with a secondary trainer capability.